Tobacco smoke filter and method



United States Patent C 2,770,241 ToBAcco sMoKE FILTER AND METHOD JosephWinkler, Queens, N. Y., assignor to American Collo Corporation, NewYork, N. Y.

Application May 10, 1954, Serial No. 428,799

7 Claims. (Cl. 131-208) It is known that tobacco smoke containsunhealthy impurities such as nicotine and various tar-like pyrogenicsubstances. These mostly liquid substances are held suspended in thetobacco smoke in the form of tiny microscopic `droplets which during thesmoking process deposit and partly become absorbed by the mucosa of themouth, nose and throat. When inhaled they travel further into thebronchial ducts and into the lungs where they exert a highly irritatingaction.

Cigarette manufacturers have been searching for means to eliminate fromthe tobacco smoke as much as possible of the irritating substances. Thisis done either by selecting less strong tobacco blends or by theincreased use of filtering devices built into the cigarette or providedfor the cigarette-holder or pipe. These conventional filters aredesigned to eliminate from the smoke as much as possible the pyrogenoustar-like substances and a great part of the nicotine itself.

Essentially, these filtering devices consist of a short hull filled withloosely packed thin fibers of cotton, a1- pha-cellulose and cellulosicmaterials in general. In order to increase the contact surface of thefibers with the smoke, the fiber layers are rolled up with thin ruffledpaper leaets. The length of such a cigarette filter is approximatelyabout 10 millimeters, its diameter is that of the cigarette or about l0millimeters.

For cigarette holders smoke lters consist of a short container filledwith small pellets of silica gel known as having absorbing propertiesfor vapors.

However, cellulosic materials and silica gel are highly hydrophilicsubstances, being primarily good absorbents for water vapors as well .asfor water soluble or Water miscible substances, like nicotine and somelow molecular water soluble resins, present in the tobacco smoke.Cellulosic materials on the other hand are very poor absorbents forwater insoluble high molecular tars and polymerized nicotinederivatives. The presence in the tobacco smoke of relatively largeamounts of Water insoluble, high molecular pyrogenic substances,belonging to the class of polycyclic, polyphenolic substances is ascientifically proven fact, and evidence is accumulating that they areto a great extent responsible for the chronic irritating action in therespiratory organs of smokers.

Therefore, no matter what an ingenious construction a tobacco smokefilter may have, the mere fact that it usually contains only hydrophilicabsorbents, incapable of retaining water insoluble hydrophobicimpurities, shows clearly that it cannot perform `properly the desiredjob, i. e. to make the smoke completely safe.

I, therefore, have conceived the new idea of using as a tobacco smokefiltering agent a highly surfaced hydrophobic material instead of ortogether with the conventional hydrophilic filtering materials, likecellulose and derivatives and silica gel. After having tested a numberof artificial highly surfaced fibers which have a low moistureretention, such like nylon, Orlon, Daeron, acrilan etc., none, however,was found as sufficiently absorbent ICC for water insoluble tar-likeconstituents of the tobacco smoke. Evidently, besides hydrophobicproperties, such material must also possess absorbent properties for thewater insoluble high molecular tars of the tobacco smoke.

I finally have found, and this is the main feature of this invention,that Ihighly surfaced polymeric materials belonging to the class oflinear or reticulated polyurethanes, such substances which contain intheir molecule the basic urethane group -C0.0.NH, and which are chieflysynthesized by reacting polyols or polyesters with organic isocyanathes,are not only highly hydrophobic but also have a great affinity totar-like polycyclic, oxygen and nitrogen containing matters, occurringin the tobacco smoke.

Highly surfaced polyurethane plastics which prove themselves to be thebest for the purpose of filtering the tobacco smoke and of removing fromit the most undesirable tars, must be open cell light foams, made fromorganic diisocyanates and polyesters, preferably in the presence ofwater. Such open cell polyurethane cellular plastic materials, having avolume density from 25 to kilograms per cubic meter, have an excellentwettability with almost the majority of fluid organic compounds,especially such which contain in the molecule oxygen, nitrogen andsulphur. They not only exhibit great absorption upon their surface butalso have the unusual ability to swell and increase their volume morethan twice when brought into contact with large amounts of highmolecular organic liquid compounds, in particular with polycyclicpolyphenols and polycy'clic nitrogen containing compounds.

In order to make a relatively short and small tobacco smoke filtersufficiently effective, the open cell polyurethane cellular plasticmaterial must contain cells as small as possible and the membranesbetween the cells must be as thin as possible and interconnected witheach other by numerous openings.

Thus for the first time this invention discloses a new method ofpurifying by the use of open cell polyurethane cellular plastics for thepurpose of filtering the tobacco smoke and of absorbing therefrom, to ahigh degree and most efficiently, the water insoluble tars and polymericnicotine derivatives which, so far, could not be efficiently eliminatedby conventional cellulosic or silica gel filters.

For most smoking purposes, filters containing only open cellpolyurethane cellular plastic are sufficient. The not absorbed, Watersoluble low molecular resins and the nicotine impart to the smoke the bymany smokers desired strong flavor, while the smoke is being filteredsubstantially free of unhealthy impurities. If, however, a very mildsmoke is preferred with a simultaneous elimination of the most of thenicotine and of the strong avoring resins, this invention provides amethod and a tobacco smoke filter which is a not hitherto knowncombination of an open cell polyurethane foam with the conventionalcellulosic fibers or silica gel pellets.

The novel features which are considered as characterstic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawings, inwhich:

Fig. l is a longitudinal cross sectional view of a cigarette and filterin accordance with the present invention;

Fig. 2 is a longitudinal cross sectional view of a cigarette and filteraccording to another embodiment of the arette holder including a lilteraccording to the present invention;

Fig. 4 is a longitudinal cross sectional view of a pipe including afilter in accordance with the present invention;

Fig. 5 is an end view of another embodiment of a cigarette filteraccording to the present invention; and

Fig. 6 is a longitudinal cross sectional View of a cigarette with aiilter according to still another embodiment of the present invention.

Referring more particularly to the drawings, specilically to Fig. 1, acigarette l is provided with tobacco 3 and at the end of the cigarettewith a filter consisting of an open cell polyurethane cellular plasticmaterial.

In Fig. 2 a cigarette 1' is provided with tobacco 3' and with a iilter2. consisting of an open cell polyurethane cellular material, andbetween the tobacco 3 and the filter 2 is a layer of cotton fibers 4.

In Fig. 3 there is illustrated a cigarette holder 5 provided with afilter 6 consisting of open cell cellular polyurethane plastic material,and in Fig. 4 a pipe 9 is priovided with a iilter consisting of an opencell cellular polyurethane plastic material.

The embodiment` of Fig. 5 consists of alternate layers of open cellpolyurethane cellular plastic material 7 and cotton felt 8 rolled intothe form of a cylinder. The embodiment of Fig. 6V consists of acigarette 1 provided with tobacco 3" and with a filter 2" consisting ofan open cell polyurethane cellular plastic material having embeddedtherein particles of silica gel 11.

The following examples illustrate the invention:

100 parts by weight of a polyester resin having an acid number of 35 andwhich was made from 3 mols of adipic acid, 31/2 mols of 1,4-butyleneglycol and 1/2 mol of glycerine, are copolymerized with 48 parts of amixture of 2,4 and 2,6-m-toluene-diisocyanate in the presence lof onepart of a 10% aqueous solution of a nonionic emulsiiier such `as AerosolOT of the American Cyanarnid Corporation; and 1/2 part lof an activatorsuch as N- methyl morplioline. After the mixed mass has reached a creamystage resembling whipped cream, it is poured into a preheated to about150 F. aluminum mold, which was previously coated with a siliconemold-release compound. This mold has preferably the followingdimensions: 1000 millimeters wide, 2000 millimeters long and 180millimeters high. The mold is covered and cured for one hour at about240 F. After cooling, -an elastic, naturally white slab is produced,which after cutting olf the upper and bottom thin skins, gives a finedense but very light and elastic open cell foam having the followingphysico-chemical properties:

Average diameter of the open cells millimeter 0.1 Average absorbingsurface in one cubic centimeter, about This material is colorless,odorless and tasteless, non tloxic, insoluble in solvents, does notpromote growth of microorganisms, and has a sparkling look. It is highlyelastic but at the same time soft in touch. More iirm foams can beeasily produced by the same method, and they are also very useful forfiltering of the tobacco smoke, but they are less economical as a foamof a density of 100 kg./m.3 will give a filter of the same volume 21/2times heavier, and consequently 21/2 times more expensive.

The resulting skinless, about 140 millimeters thick plate is now slicedinto 10 millimeters and 11/2 millimeter sheets.

Example 1 From the 10 millimeters sheet, cylinders are cut out having adiameter of 8 millimeters. Such a cylinder hav.- ing a slightly largerdiameter than the average Vdiameter of a cigarette, tits because `or itselastic compressibility perfectly into one end of the cigarette and thusprovides a tight fitting lilter for the smoke.

Example 2 Another method of manufacturing fof a tobacco smoke filterunder this invention is to place between the tobacco and thepolyurethane filter a thin, 2 millimeters thick layer of loose cottonfibers. This will insure the removal from the smoke not lonly of theundersired polycyclic water insoluble pyrogenic tars as in Example l,but also the rest of the water soluble low molecular resinousingredients of the smoke and most of the nicotine.

Example 3 As in the Example 2, a thin 2 millimeters layer of looseviscose fibers is placed between the tobacco and the rectangularfiltering piece of the polyurethane foam from -the Example 3. It .servesthe same purpose :as described in Example 3.

Example 5 Another method of manufacturing of .a tobacco smoke iilter isAto use 4the 11/2 millimeter thick sheet, and cut it into l0 millimeterswide and 2000 millimeters long strips. Said stripsr are cut into about60 millimeters long pieces. Each g piece is now 11/2 millimeter thick,l0 millimeters wide and 60 millimeters long. The strip is then rolled uptightly to a l0 millimeters long cylinder having a diameter sof about Smillimeters. Such a cylinder through gentle squeezing is tightlyinserted into the mouthpiece of a cigarette holder or pipe, or into oneend of a cigarette.

Example 6 Another method of manufacturing of a tobacco smoke Iilterembodying the invented combination of cellulosic iibers with an opencell polyurethane foam, is to proceed as follows:

The ,1%. millimeter thick sheet is again cut into 10 millimeters Wide'`and 2000 millimeters long strips. Said strips are cut into about 40millimeters long pieces. Upon each strip a one millimeter thick cottonfelt is now placed, having the same dimensions, and all this is rolledup to a cylinder l0 millimeters long and 'of a diameter of about 8millimeters. This cylinder is now, by gentle squeezing, inserted intoone end of' the cigarette, or placed into the mouthpiece of a cigaretteholder or pipe.

Example 7 Example 8 Another method of manufacturing of a tobacco smokeiilter embodying the invented combination of cellulosic libers withpolyurethane foam is to mix the shredded polyurethane foam as was donein Example 7, with line libers of alpha-cellulose in a ratio of 1:1 andto ill with itfsmall separate hulls as described in Example 7.

Example V9 Another method of manufacturing of artobacco smoke lilterembodying the invented combination of cellulosic fibers with an opencell polyurethane foam, is to place at a distance of about millimetersfrom the end of the cigarette hull an about 2 millimeters thick layer ofloosely felted cotton fibers, after this an about 6 millimeters tightlypacked layer of the shredded open cell polyurethane foam, made asdescribed in the Example 7, and finally at the end of the cigaretteagain a 2 millimeters thick layer of cotton fibers.

Example 10 Another method of manufacturing of a tobacco smoke filterembodying the invented combination of open cell polyurethane cellularplastic material with silica gel pellets is to mix shredded polyurethanefoam as described in Example 7 with silica gel pellets in a ratio of 1:1and to fill with it a small separate hull as described in the Example 7.

Of course all those methods and applications as described in theExamples 1 to 10 to provide a tobacco smoke filter for cigarettes, inmass production can be accomplished by machines, similarly built as theones which are producing cigarette filters consisting of conventionalcellulosic fibers.

Finally it is worthwhile to mention the additional valuable propertiesof filtering devices for tobacco smoke embodying open cell polyurethanefoams:

(1) The elastic resiliency of a tobacco smoke filter, containing an opencell polyurethane foam, imparts to the end of a cigarette a round feel,while held in the lips, and prevents squeezing or biting flat the end ofthe cigarette, thus unobstructing smooth smoking.

(2) While smoking, the water repellency of the open cell polyurethanefoam prevents saliva from soaking into the cigarette and obstructingsmoking.

(3) No ticklish cellulosic bers protrude from the end of the cigarettewhile the cigarette is being held in the mouth, which sometimes happenswith cigarettes containing conventional cellulosic fibers.

(4) Polyurethane cellular iilters are hygienic.

(5) A polyurethane cellular filter because of its great absorptionability for organic fluids, can be easily flavored or medicated. Thisenables for the first time the manufacture of special cigarettes whichduring smoking give up an additional taste, avor or medication forinhalation.

(6) Many smokers dislike filter cigarettes as the conventonal cellulosicfilters absorb the moisture from the smoke, thus making it dry and muchmore irritating for the respiratory tract. The polyurethane plastic foambeing hydrophobic does not deprive the smoke of its natural moisture.

I wish to be understood that I do not claim any method of manufacturingof the open cell polyurethane cellular material in any form whatsoever.I do not claim here either the usefulness of open cell polyurethanecellular plastics as filtering media for general purifying purposes.

This invention is a result of a tedious and long research for a highlysurfaced material which would have the property of a high absorbency forhigh molecular water insoluble tars occurring in the tobacco smoke andthe ensuing discovery that open cell polyurethane cellular plasticsbecause of their typical chemical composition and their unique polymericand reticulated physical structure are specific and highly etiicient forthat purpose.

I claim:

l. A tobacco smoke lter containing as a tar absorbent an open cellpolyurethane cellular plastic material.

2. A tobacco smoke filter containing as a tar absorbent an open cellpolyurethane cellular plastic material, said material being the productsof copolymerization of polyesters with organic isocyanates.

3. A tobacco smoke filtering device containing as a tar absorbent opencell polyurethane cellular plastic material, said material being made bycopolymerization of polyesters with organic isocyanates, whereby itsvolume weight is not higher than l0() kilograms per cubic meter.

4. A tobacco smoke filter consisting of open cell polyurethane cellularplastic material combined with fibers of a cellulosic material.

5. A tobacco smoke filter consisting of open cell polyurethane cellularplastic material combined with silica gel pellets.

6. A cigarette fter containing a combination of an open cellpolyurethane cellular plastic material with alphacellulose fibers.

7. A cigarette filter consisting of a combination of an open cellpolyurethane cellular plastic material with viscose rayon fibers.

References Cited in the file of this patent UNITED STATES PATENTS2,228,383 Berl Jan. 14, 1941 2,242,372 Schneider May 20, 1941 2,483,406Francis Oct. 4, 1949 2,525,497 Monfried Oct. 10, 1950 2,556,295 PaceJune 12, 1951 2,650,212 Windemuth Aug. 25, 1953 2,676,157 Newell Q---Apr. 20, 1953

